Photoresist composition

ABSTRACT

A photoresist composition comprising:
         a resin which shows an increase in solubility in an aqueous alkali solution by an action of an acid;   an acid generator;   a plasticizer; and
 
a solvent the amount of which is from 40 to 75% by mass of the total amount of the photoresist composition.

This nonprovisional application claims priority under 35U.S.C. §119 (a)on Patent Application No. 2012-130520 filed in JAPAN on Jun. 8, 2012,the entire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a photoresist composition and a methodfor producing a photoresist pattern.

BACKGROUND OF THE INVENTION

The electrodes which is a bump with height 4 to 150 μm are aligned on asubstrate in a process of mounting pins by a thin film for semiconductorchips.

As to photoresist compositions for producing a bump, JP2008-134515A1mentions a positive type chemically amplified photoresist compositionwhich optionally comprises an amine compound as a quencher.

SUMMARY OF THE INVENTION

The present application provides the inventions as follow.

[1] A photoresist composition comprising:

a resin which shows an increase in solubility in an aqueous alkalisolution by an action of an acid;

an acid generator;

a plasticizer; and

a solvent the amount of which is from 40 to 75% by mass of the totalamount of the photoresist composition.

[2] The photoresist composition according [1],wherein the resin is a resin obtained by reacting a novolak resin,a compound having two or more vinyloxy groups anda resin comprising a structural unit represented by formula (a1-2), astructural unit represented by formula (a2-1), or both of the structuralunits:

wherein R^(a1′) and R^(a2′) each independently represent a hydrogen atomor a C1-C12 hydrocarbon group where a methylene group has optionallybeen replaced by an oxygen atom or a sulfur atom, R^(a3′) represents aC1-C20 hydrocarbon group where a methylene group has optionally beenreplaced by an oxygen atom or a sulfur atom, orone of R^(a1′) and R^(a2′) is bonded to R^(a3′) to form a C2-C20divalent hydrocarbon group where a methylene group has optionally beenreplaced by an oxygen atom or a sulfur atom, and the other represents ahydrogen atom or a C1-C12 hydrocarbon group where a methylene group hasoptionally been replaced by an oxygen atom or a sulfur atom,R^(a5) represents a hydrogen atom or a methyl group,R^(a6) represents a C1-C6 alkyl group or a C1-C6 alkoxy group,and m represents an integer of 0 to 4,R^(a7) represents a hydrogen atom or a methyl group,R^(a10) represents a C1-C6 alkyl group or a C1-C6 alkoxy group, andm′ represents an integer of 0 to 4.[3] The photoresist composition according to [1] or [2], which furthercomprises a novolak resin.[4] The photoresist composition according to any one of [1] to [3],wherein the acid generator is a compound represented by formula (b5):

where R^(b1) represents a C1-C18 hydrocarbon group in which a hydrogenatom has optionally been replaced by a fluorine atom and in which amethylene group has optionally been replaced by an oxygen atom or acarboxy group.[5] The photoresist composition according to any one of [1] to [4],wherein the plasticizer is one selected from the group consisting ofphthalates, aliphatic hydrocarbon carboxylates and aromaticsulfonamides.[6] A method for producing a photoresist film with thickness 3 μm to 150μm, which comprises applying the photoresist composition according toany one of [1] to [5] to a substrate.[7] A photoresist film with thickness 3 μm to 150 μm, which is obtainedby applying the photoresist composition according to any one of [1] to[5] to a substrate.[8] A process for producing a photoresist pattern comprising:

(1) a step of applying the photoresist composition according to any oneof [1] to [6] on a substrate,

(2) a step of forming a photoresist composition film by drying thephotoresist composition,

(3) a step of exposing the photoresist composition film, and

(4) a step of developing the exposed photoresist composition film.

The photoresist composition of the present invention can provide aphotoresist film showing excellent resistance to heat and hardlycracking.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1( a), 1(b) and 1(c) illustrate a schematic cross-sectional viewof photoresist film having line and space pattern, prepared in Examples1 to 15 and Comparative example 1.

FIGS. 2( d) and 2(e) illustrate a schematic cross-sectional view ofphotoresist film having contact hole pattern, prepared in Examples 16 to17.

DESCRIPTION OF THE PREFERRED INVENTION

The photoresist composition of the present invention comprises:

a resin which shows an increase in solubility in an aqueous alkalisolution by an action of an acid;

an acid generator;

a plasticizer; and

a solvent.

The photoresist composition comprises a resin which shows increase insolubility in an aqueous alkali solution by an action of an acid, whichresin is sometimes referred to as “resin (A)”. The photoresistcomposition may comprise another resin than the resin (A).

Herein, “increase in solubility in an aqueous alkali solution by anaction of an acid” means that the solubility of resin becomes increasedby contacting it with an acid, for example that the resin is insolubleor poorly soluble in an alkali aqueous solution before contacting itwith an acid but becomes soluble in an alkali aqueous solution afterthat.

The resin (A) preferably comprises a structural unit having anacid-labile group. Hereinafter the structural unit is sometimes referredto as “structural unit (a1)”.

Herein, “an acid-labile group” means a group capable of being eliminatedby the action of an acid to form a hydrophilic group such as a hydroxylgroup or carboxy group.

Examples of the acid-labile group include a group represented by theformula (1) or the formula (2):

wherein R^(a1), R^(a2) and R^(a3) independently each represent a C1-C8alkyl group or a C3-C20 alicyclic hydrocarbon group, ortwo of R^(a1), R^(a2) and R^(a3) are bonded each other to form a C2-C20divalent hydrocarbon group and the other is a C1-C8 alkyl group or aC3-C20 alicyclic hydrocarbon group, and * represents a binding position.

wherein R^(a1′) and R^(a2′) independently each represent a hydrogen atomor a C1-C12 hydrocarbon group where a methylene group has optionallybeen replaced by an oxygen atom or a sulfur atom, and R^(a3′) representsa C1-C20 hydrocarbon group where a methylene group has optionally beenreplaced by an oxygen atom or a sulfur atom,or one of R^(a1′) and R^(a2′) represents a hydrogen atom or a C1-C12hydrocarbon group where a methylene group has optionally been replacedby an oxygen atom or a sulfur atom, and the other is bonded to R^(a3′)to form a C2-C20 divalent hydrocarbon group where a methylene group hasoptionally been replaced by an oxygen atom or a sulfur atom, andrepresents a binding position.

Specific examples of the C1-C8 alkyl group represented by R^(a1), R^(a2)and R^(a3) include a methyl group, an ethyl group, a propyl group, anisopropyl group, a butyl group, a pentyl group, a hexyl group, a heptylgroup and an octyl group.

The alicyclic hydrocarbon group represented by R^(a1), R^(a2) and R^(a3)may be monocyclic or polycyclic. Examples of the alicyclic hydrocarbongroup include a monocyclic alicyclic hydrocarbon group such as a C3-C20cycloalkyl group (e.g. a cyclopentyl group, a cyclohexyl group, amethylcyclohexyl group, a dimethylcyclohexyl group, a cycloheptyl groupand a cyclooctyl group) and a polycyclic alicyclic hydrocarbon groupsuch as a decahydronaphthyl group, an adamantyl group, a norbornylgroup, and the followings:

wherein * represents a binding position.

The alicyclic hydrocarbon group preferably has 3 to 16 carbon atoms.

When two of R^(a1), R^(a2) and R^(a3) are bonded to each other to formthe divalent hydrocarbon group, examples of the group represented by—C(R^(a1))(R^(a2))(R^(a3)) include the following groups and the divalenthydrocarbon group preferably has 3 to 12 carbon atoms.

wherein R^(a3) is the same as defined above, and * represents a bindingposition.

As the group represented by the formula (1), preferable are1,1-dialkylalkoxycarbonyl group, i.e. the group represented by theformula (1) wherein R^(a1), R^(a2) and R^(a3) independently eachrepresent a C1-C8 alkyl group, preferably a tert-butyl group; a2-alkyladamantane-2-ylxoycarbonyl group, i.e., the group represented bythe formula (1) wherein R^(a1) and R^(a2) are bonded each other to forman adamantyl ring and R^(a3) is a C1-C8 alkyl group; and1-(adaman-1-tyl)-1-alkylalkoxycarbonyl group, i.e., the grouprepresented by the formula (1) wherein R^(a1) and R^(a2) are C1-C8 alkylgroups and R^(a3) is an adamantyl group.

Examples of the hydrocarbon group represented by R^(a1′), R^(a2′) andR^(a3′) include an aliphatic hydrocarbon group, an alicyclic hydrocarbongroup, an aromatic hydrocarbon group and a combined structure of them.

Examples of the aliphatic hydrocarbon group include the alkyl group asmentioned above. Examples of the alicyclic hydrocarbon group include thesame as described above.

Examples of the aromatic hydrocarbon group include an aryl group such asa phenyl group, a naphthyl group, a p-methylphenyl group, ap-tert-butylphenyl group, a p-adamantylphenyl group, a tolyl group, axylyl group, a cumyl group, a mesityl group, a biphenyl group, aphenanthryl group, a 2,6-diethylphenyl group and a2-methyl-6-ethylphenyl group.

The group formed by combining an aliphatic hydrocarbon group and analicyclic hydrocarbon group includes methylcyclohexyl group,dimethylcyclohexyl group, methylnorbornyl group, isobornyl group and2-alkyladamantane-2-yl group, a 1-(adamantane-1-yl) alkane-1-yl group.

The group formed by combining an aliphatic hydrocarbon group and anaromatic hydrocarbon group includes an aralkyl group, specificallybenzyl group, a phenethyl group, a phenylpropyl group, a trityl group,naphthylmethyl group and naphthylethyl group.

When R^(a3′) and one of R^(a1′) and R^(a2′) are bonded to each other toform a divalent hydrocarbon group, examples of the group represented by—C(R^(a1′)) (R^(a2′)) (OR^(a3)) include the following groups and thedivalent hydrocarbon group preferably has 3 to 12 carbon atoms.

It is preferred that at least one of R^(a1′) and R^(a2′) is a hydrogenatom.

Examples of the group represented by the formula (2) include thefollowing.

wherein represents a binding position.

The monomer from which the structural unit (a1) is derived is preferablya monomer having an acid-labile group in its side chain and acarbon-carbon double bond, and is more preferably an acrylate ormethacrylate monomer having the group represented by formula (1) in itsside chain and a an acrylate or methacrylate monomer having the grouprepresented by formula (2), and still more preferably an acrylate or amethacrylate monomer having the group represented by the formula (1) inits side chain. The resin (A) may comprise one or more structural units(a1). Preferable examples of the structural units (a1) include thestructural units represented by the formulae (a1-1) and (a1-2):

In each formula, R^(a1), R^(a2), R^(a3), R^(a1′), R^(a2′) and R^(a3′)are the same meanings as above,R^(a4) and R^(a5) each independently represent a hydrogen atom or amethyl group,R^(a6) represents a C1-C8 alkyl group or a C1-C8 alkoxy group, and mrepresents an integer of 0 to 4.

In formula (a1-1), preferably each of R^(a1), R^(a2) and R^(a3) is aC1-C8 alkyl group, or two of R^(a1), R^(a2) and R^(a3) are bonded toeach other to represent C2-C20 hydrocarbon group and the otherrepresents a C1-C8 alkyl group.

R^(a2′) is preferably a C1-C12 hydrocarbon group, more preferably aC1-C12 alkyl group, and still more preferably a methyl group and anethyl group.

In formula (a1-2), R^(a1′) is preferably a hydrogen atom.

R^(a2′) is preferably a C1-C12 hydrocarbon group, more preferably aC1-C12 alkyl group, and still more preferably a methyl group and anethyl group.

The hydrocarbon group represented by and R^(a3′) includes preferably aC1-C18 alkyl group, a C3-C18 alicyclic hydrocarbon group, a C6-C18aromatic hydrocarbon group, and a combined group of them, morepreferably a C1-C18 alkyl group, a C3-C18 alicyclic hydrocarbon group,and C7-C18 aralkyl group. The alkyl group and the alicyclic hydrocarbongroup are preferably unsubstituted. When the aromatic hydrocarbon grouphas been substituted, the substituent is a C6-C10 aryloxy group.

R^(a5) is preferably a hydrogen atom.

R^(a6) is preferably a C1-C4 alkoxy group, and more preferably a methoxyand ethoxy group, and still more preferably methoxy group.

m is preferably 0 or 1, and more preferably 1.

Examples of the structural unit represented by formula (a1-1) includeone represented by formulae (a1-1-1) to (a1-1-17).

Examples of the structural unit represented by formula (a1-2) includeone derived from the monomer represented by any one of formulae (a1-2-1)to (a1-2-8).

When the resin comprises the structural unit represented by formula(a1-1) and/or formula (a1-2), the total content of these structuralunits is usually 10 to 95% by mole and preferably 15 to 90% by mole,more preferably 25 to 85% by mole, and still more preferably 20 to 60%by mole based on total molar of all the structural units of the resin.

The resin preferably may comprise a structural unit having noacid-labile group, in addition to the structural unit having anacid-labile group. The resin can have two or more kinds of structuralunits having no acid-labile group. The structural unit having noacid-labile group preferably comprises a hydroxyl group or a lactonering. When the resin comprises the structural unit having no acid-labilegroup, the content ratio of the structural unit having an acid-labilegroup to the structural unit having no acid-labile group, i.e., [thestructural unit having an acid-labile group]:[the structural unit havingno acid-labile group] is preferably 10:90 to 80:20, more preferably20:80 to 60:40, on the molar base.

Examples of the structural unit represented by formula (a2) include onerepresented by formulae (a2-1), (a2-2) and (a2-3).

wherein R^(a7), R^(a8) and R^(a9) independently represent a hydrogenatom or a methyl group,R^(a10) represents a C1-C6 alkyl group or a C1-C6 alkoxy group,m′ represents an integer of 0 to 4,R^(a11) represents a C1-C10 monovalent or divalent hydrocarbon group,R^(a12) represents a C1-C6 alkyl group,L^(a1) represents a C1-C6 monovalent or divalent alkanediyl group, andn′ represents an integer of 1 to 30.

Examples of the alkyl group in formulae (a2-1), (a2-2) and (a2-3)include a methyl group, an ethyl group, a propyl group, a butyl group, apentyl group and a hexyl group.

Examples of the alkoxy group include a methoxy group, an ethoxy group, apropoxy group, a butoxy group, a pentyloxy group and a hexyloxy group.

Examples of the alkanediyl group include linear alkanediyl groups suchas methylene group, ethylene group, propane-1,3-diyl group,butane-1,4-diyl group, pentane-1,5-diyl group, and hexane-1,6-diylgroup; and branched alkanediyl groups such as a propane-1,2-diyl group,a pentane-1,4-diyl group, and a 2-methylbutane-1,4-diyl group.

The hydrocarbon group represented by R^(a11) includes a methyl group, anethyl group, a propyl group, a butyl group, a pentyl group, a hexylgroup, a heptyl group, and an octyl group. The alicyclic hydrocarbongroup includes a C3-C10 cycloalkyl group such as a cyclohexyl group, acycloheptyl group, or an adamantyl group.

The aromatic hydrocarbon group includes a phenyl group or a naphtylgroup.

R^(a7) preferably represents a hydrogen atom.

R^(a10) represents preferably a C1-C4 alkoxy group, more preferably amethoxy group or an ethoxy group, and still more preferably a methoxygroup.

m′ represents preferably an integer of 0 or 1, more preferably aninteger of 0.

R^(a11) represents preferably a C1-C6 monovalent or divalent alkylgroup, a C5-C10 alicyclic hydrocarbon group and a C6-C10 aromatichydrocarbon group.

L^(a1) represents preferably an ethane-1,2-diyl group, apropane-1,3-diyl group and a butane-1,2-diyl group, more preferably anethane-1,2-diyl group.

n represents preferably an integer of 1 to 10.

Examples of the structural unit represented by formula (a2-1) includethose represented by formulae (a2-1-1), (a2-1-2), (a2-1-3) and (a2-1-4).The monomers from which the structural units represented by formula(a2-1) are derived are mentioned in JP2010-204634A1.

Examples of the monomers from which the structural units represented byformula (a2-2) are derived include alkyl(meth)acrylates such asmethyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate,butyl(meth)acrylate, hexyl(meth)acrylate, cycloalkyl(meth)acrylates suchas cyclopentyl(meth)acrylate and cyclohexyl(meth)acrylate,

polycyclic(meth)acrylates such as adamantyl(meth)acrylate, andaryl(meth)acrylates such as phenyl(meth)acrylate andbenzyl(meth)acrylate.

Herein, “(meth)acrylate” includes acrylate and methacrylate. Examples ofthe monomers from which the structural units represented by formula(a2-3) are derived include (meth)acrylates such asethyleneglycolmonomethylether(meth)acrylate,ethyleneglycolmonoethylether (meth)acrylate,ethyleneglycolmonopropylethylether (meth)acrylate,ethyleneglycolmonobuthylether (meth)acrylate,diethyleneglycolmonomethylether (meth)acrylate,triethyleneglycolmonomethylether (meth)acrylate,tetraethyleneglycolmonomethylether (meth)acrylate,pentaethyleneglycolmonomethylether (meth)acrylate,hexaethyleneglycolmonomethylether (meth)acrylate,nonaethyleneglycolmonomethylether (meth)acrylate, andoctaethyleneglycolmonomethylether (meth)acrylate.

Examples of the monomers from which the structural unit represented byformula (a2) is derived include acrylate, methacrylate, crotonic acid,2-hydroxyethyl(meta)acrylate, 2-hydroxypropyl(meta)acrylate, styrene,α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene,4-methoxystyrene, and 4-isopropoxystyrene.

Examples of resin (A) include what comprises the combinations ofstructural units, as represented by the following formulae (A1-1) to(A1-19).

The resin (A) preferably comprises the structural unit represented byformula (a1) and the structural unit represented by formula (a2), morepreferably the structural unit represented by formula (a1-1) and/orformula (a1-2) as well as the structural unit represented by formula(a2).

The resin (A) can generally be produced by polymerizing theabove-mentioned monomers in a known manner such as radicalpolymerization.

The average weight molecule weight of the resin (A) is preferably 10000or more, more preferably 15000 or more, and 600000 or less, morepreferably 500000 or less.

Herein, the weight-average molecular weight can be determined by gelpermeation chromatography using standard polystyrene as a standardreference material. The detailed condition for the chromatography isdescribed in Examples of the present application.

Another preferred example of the resin (A) includes a resin obtained byreacting

a novolak resin,a compound having two or more vinyloxy groups, which is sometimesreferred to as “vinyl ether compound” and a resin comprising astructural unit represented by formula (a1-2), a structural unitrepresented by formula (a2-1), or both of the structural units.

The novolak resin is a resin obtained by condensing a phenol compoundwith an aldehyde in the presence of a catalyst. Examples of the phenoliccompound include phenol, o-, m- or p-cresol, 2,3-, 2,5-, 3,4- or3,5-xylenol, 2,3,5-trimethylphenol, 2-, 3- or 4-tert-butylphenol,2-tert-butyl-4- or 5-methylphenol, 2-, 4- or 5-methylresorcinol, 2-, 3-or 4-methoxyphenol, 2,3-, 2,5- or 3,5-dimethoxyphenol,2-methoxyresorcinol, 4-t-butylcatechol, 2-, 3- or 4-ethylphenol, 2,5- or3,5-diethylphenol, 2,3,5-triethylphenol, 2-naphthol, 1,3-, 1,5- or1,7-dihydroxynaphthalene, and polyhydroxytriphenylmethane compoundsobtained by condensing xylenol with hydroxybenzaldehyde. One or more ofthese phenolic compounds can be used for producing the other resin.Among them, the phenolic compound is preferably o-cresol, m-cresol,p-cresol, 2,3-xylenol, 2,5-xylenol, 3,4-xylenol, 3,5-xylenol,2,3,5-trimethylphenol, 2-t-butylphenol, 3-t-butylphenol,4-t-butylphenol, 2-t-butyl-4-methylphenol or 2-t-butyl-5-methylphenol.

Examples of the aldehyde include aliphatic aldehydes such asformaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde,isobutyraldehyde, acrolein or croton aldehyde; alicyclic aldehydes suchas cyclohexanealdehyde, cyclopentanealdehyde, furfural, andfuranacrolein; aromatic aldehydes such as benzaldehyde, o-, m- orp-methylbenzaldehyde, p-ethylbenzaldehyde, 2,4-, 2,5-, 3,4- or3,5-dimethylbenzaldehyde or o-, m- or p-hydroxybenzaldehyde; andaromatic aliphatic aldehydes such as phenylacetaldehyde orcinnamaldehyde.

One or more of these aldehydes can be used for producing the otherresin. Among them, formaldehyde is preferred in view of easy industrialavailability.

The catalyst for condensation of a phenolic compound and an aldehydeincludes inorganic acids such as hydrochloric acid, sulfuric acid,perchloric acid or phosphoric acid; organic acid such as formic acid,acetic acid, oxalic acid, trichloroacetic acid or p-toluenesulfonicacid; divalent metal salts such as zinc acetate, zinc chloride or aceticacid magnesium.

One or more of these catalysts can be used for producing the otherresin. The amount of the catalyst to be used is usually from 0.01 to 1mole per mole of aldehyde.

The condensation of a phenolic compound and an aldehyde can be conductedin a known manner. The condensation can be conducted by mixing aphenolic compound and an aldehyde, followed by reacting them at thetemperature in the range of 60° C. to 120° C. for 2 to 30 hours. Thecondensation can be conducted in the presence of a solvent such asmethylethylketone, methylisobuthylketone and acetone. After thereaction, novolak resins can be collected by adding a solvent insolublein water to the reaction mixture, washing the mixture with water,followed by condensing it. Examples of the resin comprising a structuralunit represented by formula (a1-2) or formula (a2-1), which is sometimesreferred to as “poly(hydroxystyrene)-based resin”, includepoly(o-hydroxystyrene), poly(m-hydroxystyrene) andpoly(p-hydroxystyrene), preferably poly(p-hydroxystyrene), which iscommercially available and can be produced according to a known method.

As the vinyl ether compound, a compound having two vinyl etherstructures may be used and a compound having more than three vinyl etherstructures may be used. The compound having two vinyl ether structuresis preferable. Herein, “the vinyl ether structure” means the followingstructure: —CH₂—O—CH═CH₂.

Specific examples of the vinyl ether compound include1,4-bis(vinyloxymethyl)cyclohexane and 1,2-bis(vinyloxy)ethane, and1,4-bis(vinyloxymethyl)cyclohexane is preferable.

As the vinyl ether compound, a commercially available one is usuallyused.

The content to be used of the novolak resin and thepoly(hydroxystyrene)-based resin is from 30/70 to 70/30 on mass basis.

The content to be used of vinyl ether compound is preferably from 1 to30 parts by mass, more preferably from 2 to 10 parts by mass per 100parts by mass of the total amount of novolak resin andpoly(hydroxystyrene)-based resin.

The resin obtained by reacting novolak resin, vinyl ether compound andpoly(hydroxystyrene)-based resin includes those mentioned inJP2008-134515A1 and JP2008-46594A1, which can be prepared by the methoddescribed these documents. The weight average molecular weight of theresin obtained by reacting novolak resin, vinyl ether compound andpoly(hydroxystyrene)-based resin is preferably 5000 or more, morepreferably 10000 or more, and preferably 300000 or less, more preferably200000 or less.

The photoresist composition of the present invention may furthercomprise another resin than the resin (A). Hereinafter The other resinis preferably an alkaline-soluble resin. The alkaline-soluble resinmeans a resin which comprises an acid group and soluble in an alkalinedeveloper. The acid group includes a carboxy group, a sulfo group, or aphenolic-hydroxy group.

The alkaline-soluble resin includes known resins in the art such asnovolak resins and vinyl resins which comprises no structural unit (a1).As the alkaline-soluble resin, a novolak resin is preferred.

Specific examples of novolak resin as the alkaline-soluble resin includethose as mentioned above.

Phenol resin for producing novolak resin includes preferably o-cresol,m-cresol, p-cresol, 2,3-xylenol, 2,5-xylenol, 3,4-xylenol, 3,5-xylenol,2,3,5-trimethylphenol, 2-t-butylphenol, 3-t-butylphenol,4-t-butylphenol, 2-t-butyl-4-methylphenol or 2-t-butyl-5-methylphenol.The aldehyde for producing novolak resin is preferably formaldehyde.

The weight average molecular weight of novolak resin is preferably 3000or more, more preferably 4000 or more, still more preferably 5000 ormore, and preferably 50000 or less, more preferably 30000 or less, stillmore preferably 15000 or less.

The content of the resin in the photoresist composition of the presentinvention is preferably 80% by mass or more, and preferably 99% by massor less, of the total amount of solid components.

In this specification, “solid components” means components other thansolvent in the photoresist composition.

The content of resin (A) is preferably 10% to 100% by mass, morepreferably 30% to 100% by mass, of the total amount of the resin.

If the photoresist composition of the present invention furthercomprises an alkali-soluble resin, it comprises preferably the resin (A)and novolak resin.

The content ratio of the resin (A) and novolak resin, which isrepresented by [the content of resin (A)]:[the content of novolakresin], is preferably from 90:10 to 30:70, more preferably from 80:20 to40:60, still more preferably from 65:35 to 45:55, by mass ratio.

The photoresist composition of the present invention comprises an acidgenerator.

The acid generator is a compound which can be decomposed by light orradiation to generate an acid. The acid generators may be either ionicor non-ionic one. The acid generator can be used singly or as a mixtureof two or more thereof. The non-ionic acid generator includes organichalide, sulfonate esters (e.g., 2-nitrobenzylester, aromatic sulfonate,oxime sulfonate, N-sulfonyloxyimide, N-sulfonyloxyimide, sulfonyloxyketone, diazonaphthoquinone 4-sulfonate) and sulfone (e.g.,disulfone, ketosulfone, sulfonyldiazomethane). The ionic acid generatorincludes an onium salt comprising an onium cation (e.g., adiazoniumsalt, a phosphonium salt, a sulfonium salt, an iodonium salt).

Anions of the onium salts include a sulfonic acid anion, a sulfonylimideanion and a sulfonylmethide anion.

The acid generator includes compounds which generate an acid uponradiation, which are described in JP63-26653A1, JP 55-164824A1,JP62-69263A1, JP63-146038A1, JP63-163452A1, JP 62-153853A1,JP63-146029A1, U.S. Pat. No. 3,779,778, U.S. Pat. No. 3,849,137, Germanpatent No. 3914407 and European patent No. 126712.

The non-ionic acid generator is preferably a compound which comprises agroup represented by formula (B1).

where R^(b1) represents a C1-C18 hydrocarbon group which optionally hasa fluorine atom and in which a methylene group optionally has beenreplaced by an oxygen atom or a carbonyl group.

The hydrocarbon group represented by R^(b1) includes

C1-C18 alkyl groups such as a methyl group, an ethyl group, a propylgroup, an isopropyl group, a butyl group, a pentyl group, a hexyl group,a heptyl group, an octyl group, decyl group or dodecyl group,

C3-C18 alicyclic hydrocarbon groups such as a monocyclic alicyclichydrocarbon group such as a C3-C18 cycloalkyl group (e.g. a cyclopentylgroup, a cyclohexyl group, methylcyclohexyl group, a dimethylcyclohexylgroup, a cycloheptyl group and a cyclooctyl group) and a polycyclicalicyclic hydrocarbon group (e.g. adecahydronaphthyl group, an adamantylgroup, a norbornyl group),

C6-C18 aromatic hydrocarbon groups such as a phenyl group, a naphthylgroup, a p-methylphenyl group, a p-tert-butylphenyl group, ap-adamantylphenyl group, a tolyl group, a xylyl group, a cumyl group, amesityl group, a biphenyl group, a phenanthrylgroup, a 2,6-diethylphenyl group and a 2-methyl-6-ethylphenyl group andother groups such as aralkyl group.

The hydrocarbon group is preferably a C1-C10 alkyl group and a C6-C10aromatic hydrocarbon group, and more preferably a C1-C8 alkyl group, andstill more preferably a C1-C4 alkyl group.

The hydrocarbon group in which a methylene group has been replaced by anoxygen atom or a carbonyl group includes those represented by formulae(Y1) to (Y12), preferably those represented by formulae (Y7) to (Y9),more preferably one represented by formula (Y9).

The hydrocarbon group which has a fluorine atom includes fluoroalkylgroups such as a fluoromethyl group, a fluoroethyl group, a fluoropropylgroup, a fluorobutyl group, a fluoropentyl group, a fluorohexyl group, afluoroheptyl group and a fluorooctyl group; alicyclic fluorohydrocarbongroups such as C3-C10 fluorocycloalkyl groups;

aromatic fluorohydrocarbon groups such as a fluorophenyl group andfluoronaphtyl group, and a combined structure of them. The hydrocarbongroup which has a fluorine atom is preferably a C1-C10 fluoroalkyl groupand a C6-C10 aromatic fluorohydrocarbon group, and more preferably aC1-C8 perfluoroalkyl group, and still more preferably a C1-C4perfluoroalkyl group.

The compound represented by formula (B1) includes those represented byformulae (b1), (b2), (b3) and (b4), preferably those represented byformulae (b1), (b2) and (b3), more preferably those represented byformulae (b1) and (b3), and still more preferably those represented byformula (b1).

where R^(b1) is as defined above, R^(b2), R^(b3) and R^(b4) eachindependently represent a hydrogen atom, a C1-C5 alkyl group or a C1-C5alkoxy group, and the ring W^(b1) represents a C6-C14 aromatichydrocarbon ring which can have a substituent and a C6-C14 aromaticheterocyclic group which optionally has a substituent.

The alkyl group represented by R^(b2), R^(b3) and R^(b4) includes amethyl group, an ethyl group, a propyl group, a butyl group, and apentyl group, preferably a methyl group.

The alkoxy group represented by R^(b2), R^(b3) and R^(b4) includes amethoxy group, an ethoxy group, a propoxy group, a butoxy group, and apentyloxy group, preferably a methoxy group.

The aromatic hydrocarbon ring represented by the ring W¹ includes abenzene ring, a naphthalene ring, and anthracene ring.

The aromatic heterocyclic group represented by the ring W^(b1) may havea sulfur or oxygen atom, which includes the following ones:

The substituent which the ring W^(b1) optionally has includes a C1-C5alkyl group.

The ring W^(b1) is preferably a naphthalene ring, more preferably anunsubstituted naphthalene ring.

The compound represented by formula (b1) is preferably a compoundrepresented by any one of formulae (b5) to (b8), more preferably thecompound represented by formula (b5).

where R^(b1) is as defined above, R^(b5), R^(b6) and R^(b7) eachindependently represent a hydrogen atom, or a C1-C5 alkyl group.

Specific examples of the compound represented by formula (b1) includepreferably a compound represented by any one of formulae (b1-1) to(b1-11), more preferably a compound represented by any one of formulae(b1-5) to (b1-11), and still more preferably a compound represented byany one of formulae (b1-6) and (b1-7).

Specific examples of the compound represented by formula (b2) includethe following compounds.

Specific examples of the compound represented by formula (b3) includethe following compounds.

Specific examples of the compound represented by formula (b4) includethe following compounds.

The ionic acid generator is a compound represented by formula (b9) or(b10).

where A^(b1) and A^(b2) each independently represent an oxygen atom or asulfur atom,

R^(b8), R^(b9), R^(b10) and R^(b11) each independently represent aC1-C10 alkyl group or a C6-C12 aromatic hydrocarbon group, and X1⁻ andX2⁻ each independently represent an organic anion.

The alkyl groups represented by R^(b8), R^(b9), R^(b10) and R^(b11)include a methyl group, an ethyl group, a propyl group, a butyl group, apentyl group, a hexyl group, a heptyl group and an octyl group.

The aromatic hydrocarbon groups represented by R^(b8), R^(b9), R^(b10)and R^(b11) include an aryl group such as phenyl group, a naphthylgroup, an anthryl group, p-methylphenyl group, p-tert-buthylphenylgroup, p-adamantylphenyl group, tolyl group, xylyl group, a cumenylgroup, a mesityl group, a biphenyl group, a phenanthryl group, a2,6-diethylphenyl group, and 2-methyl-6-ethylphenyl.

R^(b8), R^(b9), R^(b10) and R^(b11) are preferably a C6-C12 aromatichydrocarbon group, more preferably a phenyl group.

Examples of X1⁻ and X2⁻ include sulfonic acid anion, bis(alkylsulfonyl)amide anion and tris(alkylsulfonyl) methide anion. Preferable is asulfonic acid anion, specifically a sulfonic acid anion represented byformula (b11).

where R^(b22) represents a C1-C18 hydrocarbon group which may havefluorine atoms and in which the methyl group may be substituted with anoxygen atom or a carbonyl group.

Examples of R^(b12) include those of R^(b1).

The compound represented by formula (b9) includes the followingcompounds.

The compound represented by formula (b10) includes the followingcompounds.

The acid generator is available on the market, or it can be prepared bya known method.

The content of the acid generator is preferably 0.5 to 30 parts byweight, more preferably 1 to 25 parts by weight, per 100 parts of thetotal resin.

The photoresist composition of the present invention further comprises aplasticizer.

Herein, the plasticizer means a compound providing plasticity with apolymer.

The plasticizer includes phthalates, aliphatic hydrocarbon carboxylates,aromatic polyhydric carboxylates, polyolether esters, and sulfonateester and aromatic sulfonamides.

Phthalate includes benzyloctyl phthalate, dimethyl phthalate, dibutylphthalate, diheptyl phthalate, bis(2-ethylhexyl) phthalate,bis(2-butoxyethyl) phthalate, diisodecyl phthalate, isononyl phthalate,butylbenzyl phthalate, ethylphthalyl ethylglycolate, butylphthalylglycolate and are preferably ethylphthalyl ethylglycolate.

Aliphatic hydrocarbon carboxylates include dimethyl adipate, diethyladipate, bis(2-ethylhexyl) adipate, bis(2-ethylhexyl) azelate,diisopropyl adipate, dibutyl adipate, diisobutyl adipate, dipropyladipate, dimethyl azelate, di-n-alkyl adipate, diisononyl adipate,bis(2-butoxyethyl) adipate, dibutyl fumarate, bis(2-ethylhexyl)fumarate, dibutylmaleate, diethyl maleate, maleate bis(2-ethylhexyl),dimethyl maleate, ethyl oleate, butyl oleate, dibutyl sebacate, diethylsebacate, bis(2-ethylhexyl) sebacate, dimethyl sebacate, di-n-octylsebacate, diethyl succinate, isodecyl succinate, O-acetyltriethylcitrate, O-acetyltributyl citrate, O-acetylmethyl ricinoleiate,tri-butyl citrate, triethyl citrate, trimethyl citrate, and tri-propylcitrate, and preferably diisononyl adipate, bis(2-ethylhexyl) sebacate,O-acetyltributyl citrate.

The aromatic polyhydric carboxylates include trimellitate such astris(2-ethylhexyl)trimellitate.

The polyolether esters include diethyleneglycoldibutylether,diethyleneglycoldiacetate, diethyleneglycoldibenzoate, monooleine,triacetin, tributyrin, and triethyleneglycol diacetate.

The sulfonates include phenyl pentadecanesulfonate and phenylhexadecanesulfonate.

The aromatic sulfoneamides include N-butylbenzenesulfonamide,N-ethylbenzenesulfonamide, N-ethyl-o,p-toluenesulfonamide,N,N′-dibutylbenzenesulfonamide, and N-propylbenzenesulfonamide, andpreferably N-butylbenzenesulfonamide.

The plasticizer is preferably one selected from the group consisting ofphthalates, aliphatic hydrocarbon carboxylates, aromaticpolyhydriccarboxylates, and aromatic sulfonamides, more preferably oneselected from the group consisting of phthalates, aliphatic hydrocarboncarboxylates, and aromatic sulfonamides.

Specifically preferred are ethylphthalylethyl glycolate,N-butylbenzenesulfoneamide, O-acetyltributyl citrate,tris(2-ethylhexyl)trimellitate, diisononyl adipate, bis(2-ethylhexyl)sebacate and dihexyl phthalate, more preferred areethylphthalylethylglycolate, tris(2-ethylhexyl)trimellitate, diisononyladipate, bis(2-ethylhexyl) sebacate, O-acetyltributyl citricate andN-butylbenzene sulfonamide, and

still more preferred are one selected from the group consisting ofethylphthalylethylglycolate, O-acetyltributyl citricate andN-butylbenzene sulfonamide.

The photoresist composition of the present invention comprises aquencher.

Herein, the quencher is a compound capable of trapping an acid generatedfrom an acid generator by exposure. The quencher includes a basicnitrogen-containing organic compound.

The basic nitrogen-containing organic compound includes amines andammonium salts.

The amines include primary, secondary or tertiary, aliphatic oralicyclic, amines.

Specific examples of the amines include those represented by formulae(C1) and (C2);

wherein R^(c1), R^(c2) and R^(c3) independently represent a hydrogenatom, a C1-C6 alkyl group, a C5-C10 alicyclic hydrocarbon group, or aC6-C10 aromatic hydrocarbon group,the alkyl group and the alicyclic hydrocarbon group can have asubstituent selected from the group consisting of a hydroxy group, anamino group and a C1-C6 alkoxy group, and the aromatic hydrocarbon grouphas a substituent selected from the group consisting of a C1-C6 alkylgroup, a C1-C6 alkoxy group, and a C5-C10 alicyclic hydrocarbon group.

wherein the ring W¹ is a nitrogen-containing heterocyclic ring, or abenzene ring having a substituted or unsubstituted amino group and theheterocyclic ring and the benzene ring can have a hydroxyl group orC1-C4 alkyl group,A¹ represents a phenyl group or a naphtyl group, andn represents an integer of 2 or 3.

The substituted or unsubstituted amino group is specifically representedby —NR¹R¹ where R¹ and R² each independently represent a hydrogen atom,a C1-C10 aliphatic hydrocarbon group, a C3-C10 alicyclic hydrocarbongroup, a C6-C14 aromatic hydrocarbon group.

The aliphatic hydrocarbon group includes alkyl groups such as a methylgroup, an ethyl group, a propyl group, butyl group, a pentyl group, ahexyl group, a heptyl group and an octyl group.

The alicyclic hydrocarbon group includes a C3-C10 cycloalkyl group suchas a cyclopentyl group, a cyclohexyl group, a methylcyclohexyl group, adimethylcyclohexyl group, a cycloheptyl group and a cyclooctyl group,and a polycyclic alicyclic hydrocarbon group such as a decahydronaphthylgroup, an adamantyl group, a norbornyl group.

The aromatic hydrocarbon group includes an aryl group such as a phenylgroup, a naphthyl group, a p-methylphenyl group, a p-tert-butylphenylgroup, a p-adamantylphenyl group, a tolyl group, a xylyl group, a cumylgroup, a mesityl group, a biphenyl group, an anthryl group, aphenanthryl group, a 2,6-diethylphenyl group and a2-methyl-6-ethylphenyl group.

Herein, the nitrogen-containing heterocyclic ring means a heterocyclicring which has a nitrogen atom as its ring-constituting atom.

The nitrogen-containing heterocyclic ring may be aromatic ornon-aromatic, which may have another hetero atom such as an oxygen atomor sulfur atom. The heterocyclic ring has usually 1 to 3 nitrogen atoms.The heterocyclic ring represented by W¹ includes the rings representedby formulae (Y13) to (Y28).

The ring W¹ is preferably a 5- to 6-membered aromatic heterocyclic ring,specifically a ring represented by any one of formulae (Y20) to (Y25).

Examples of the compound represented by the formula (C1) includediphenylamine, hexylamine, heptylamine, octylamine, nonylamine,decylamine, dibutylamine, dipentylamine, dihexylamine, diheptylamine,dioctylamine, dinonylamine, didecylamine, triethylamine, trimethylamine,tripropylamine, tributylamine, tripentylamine, trihexylamine,triheptylamine, trioctylamine, trinonylamine, tridecylamine,methyldibutylamine, methyldipentylamine, methyldihexylamine,methyldicyclohexylamine, methyldiheptylamine, methyldioctylamine,methyldinonylamine, methyldidecylamine, ethyldibutylamine,ethydipentylamine, ethyldihexylamine, ethydiheptylamine,ethyldioctylamine, ethyldinonylamine, ethyldidecylamine,dicyclohexylmethylamine, tris[2-(2-methoxyethoxy)ethyl]amine,triisopropanolamine, ethylenediamine, tetramethylenediamine, andhexamethylenediamine.

Examples of the compound represented by the formula (C2) includecompounds represented by formulae (I-1) to (I-11), preferably compoundsrepresented by formulae (I-2) to (I-8).

The compound represented by formulae (C1) and (C2) can be prepared by aknown method, which is available on the market.

The content of the quencher is preferably 0.01 to 4%, more preferably0.02 to 3% based on sum the solid components of the photoresistcomposition.

The photoresist composition of the present invention usually comprises asolvent. Examples of the solvent include a glycol ether ester such asethyl cellosolve acetate, methyl cellosolve acetate and propylene glycolmonomethyl ether acetate; a glycol ether such as propylene glycolmonomethyl ether; an acyclic ester such as ethyl lactate, butyl acetate,amyl acetate and ethyl pyruvate; a ketone such as acetone, methylisobutyl ketone, 2-heptanone and cyclohexanone; and a cyclic ester suchas γ-butyrolactone.

The amount of the solvent is generally 40% by weight or more, preferably42% by weight or more preferably 45% by weight or more of the totalamount of the photoresist composition of the present invention. Theamount of the solvent is generally 75% by weight or less, preferably 70%by weight or less, and more preferably 68% by weight or less, of thetotal amount of the photoresist composition of the present invention.

Since the photoresist composition comprises a solvent within theabove-mentioned range, it can easily form a composition film withthickness 3 μm to 150 μm. When the amount of the solvent falls withinthe above-mentioned range, the photoresist composition can easilyprovide a thick photoresist film with a flat surface.

The photoresist composition of the present invention may comprise ifnecessary, a small amount of various additives such as a sensitizer, adissolution inhibitor, other polymers, a surfactant, a stabilizer and adye as long as the effect of the present invention is not prevented.

The photoresist composition of the present invention can usually beprepared by mixing, in a solvent, an acid generator, the resin (A), aplasticizer, and if necessary a quencher or other additives, at asuitable ratio for the composition, optionally followed by filtratingthe mixture with a filter having from 0.1 μm to 50 μm of a pore size.

The order of mixing these components is not limited to any specificorder. The temperature at mixing the components is usually 10 to 40° C.,which can be selected depending on the resin or the like. The mixingtime is usually 0.5 to 24 hours, which can be selected in view of thetemperature. The means for mixing the components is not limited tospecific ones, which includes a stirrer.

The amounts of the components in the photoresist compositions can beadjusted by selecting the amount to be used for production of them.

The method of the present invention comprises the following steps (1) to(4):

(1) a step of applying the photoresist composition of the presentinvention on a substrate,

(2) a step of forming a photoresist composition film by drying thecomposition,

(3) a step of exposing the film to radiation, and

(4) a step of developing the exposed film to form a photoresist pattern.

The applying of the composition on a substrate is usually conductedusing a conventional apparatus such as spin coater.

The substrate includes silicon wafers on which semiconductor elements(e.g., a transistor, a diode) may be formed in advance.

If the photoresist composition is to be used for bump formation, asubstrate on which a conductive material has been laminated ispreferred. Such conductive material includes an alloy which comprises ametal selected from the group consisting of gold (Au) copper (Cu),nickel (Ni), tin (Sn), palladium (Pd) and silver (Ag), or alloyscomprising a metal selected from the group. Preferred is copper or analloy comprising copper.

The substrate may be washed or coated with a reflect-preventing layersuch as one containing hexamethyldisilazane.

For forming the reflect-preventing layer, such composition for organicreflect-preventing layer as available on the market can be used.

The photoresist composition film is usually formed by drying the appliedcomposition with a heating apparatus such as hot plate or adecompressor, to thereby dry off the solvent. The heating temperature ispreferably 50 to 200° C., and the operation pressure is preferably 1 to1.0*10⁵ Pa.

The thickness of the film obtained by step (2) is in the range ofpreferably 3 μm to 150 μm, more preferably 4 μm to 100 μm.

The film is exposed to radiation using an exposure system. The exposureis usually conducted through a mask having a pattern corresponding to adesired photoresist pattern. The exposure source includes known one,preferably gray (wavelength: 436 nm), h ray (wavelength: 405 nm) and iray (wavelength: 365 nm).

The process may further comprise baking the exposed film, so calledpost-exposure bake, after step (3).

The step of baking the exposed film is conducted with heating means suchas hot plates. The deprotection reaction further proceeds bypost-exposure bake.

The temperature of baking the exposed film is preferably 50 to 200° C.,and more preferably 60 to 120° C. The time of baking is usually 40 to400 seconds, preferably 50 to 350 seconds.

The development of the exposed or baked photoresist composition film isusually carried out with an alkaline developer using a developmentapparatus.

The alkaline developer to be used may be any one of various alkalineaqueous solution to be used in the art. Generally, an aqueous solutionof tetramethylammonium hydroxide or (2-hydroxyethyl)trimethylammoniumhydroxide (commonly known as “choline”) is often used.

After development, the formed photoresist pattern is preferably washedwith ultrapure water, and the remained water on the photoresist patternand the substrate is preferably removed.

The photoresist composition of the present invention can provide thickphotoresist films which can have fine photoresist pattern, therefore thecomposition is suitable for producing bumps.

A photoresist composition for producing a photoresist film withthickness 3 μm to 150 μm, which comprises the above-mentioned resin, anacid generator, a plasticizer, and a solvent is one aspect of thepresent invention.

The photoresist composition of the present invention is useful as amaterial for producing bumps.

Bumps can be produced by the process comprising the following steps;

laminating a conductive material (e.g. seed metal) on a wafer which mayhave semiconductor elements thereon to thereby form a conductive film,

producing a photoresist pattern on the conductive film by the method ofthe present invention,

pattern plating an electrode material such as Cu, Ni or solder, usingthe photoresist pattern as its mold, and

removing the photoresist film and the conductive film from the device byetching or the like, optionally followed by removing the electrodematerial by heat-melting the electrode material.

EXAMPLES

The present invention will be described more specifically by Examples,which are not construed to limit the scope of the present invention.

The “%” and “part(s)” used to represent the content of any component andthe amount of any material used in the following examples andcomparative examples are on a weight basis unless otherwise specificallynoted.

The weight-average molecular weight of any material used in thefollowing examples is a value determined by gel permeationchromatography under the following conditions.

Equipment: HLC-8120GPC type, manufactured by TOSOH CORPORATION

Column: Three of TSKgel Multipore HXL-M with guard column, manufacturedby TOSOH CORPORATION

Solvent: tetrahydrofuran

Flow rate: 1.0 mL/min.

Detector: RI Detector

Column temperature: 40° C.

Injection volume: 100 μL

Standard reference material: standard polystyrene, manufactured by TOSOHCORPORATION

Synthesis Example 1

Twenty (20) parts of polyvinylphenol (Trade name VP-15000, Product ofNippon Soda Co., Ltd.) was dissolved in 240 parts ofmethylisobutylketone, followed by concentrating it with an evaporator.

To a four-necked flask with a stirring device, a reflux condenser and athermometer, the concentrated mixture and 0.003 parts ofp-toluenesulfonic acid dehydrates were poured and then 5.05 parts ofethylvinylether was dropped thereinto at a temperature of 20 to 25° C.over 10 minutes. The obtained mixture was stirred at the above-mentionedtemperature for 2 hours and then diluted with 200 parts ofmethylisobutylketone, followed by washing it with ion-exchanged waterfive times. The washed mixture was concentrated until its amount became45 parts using an evaporator, and 150 parts ofpropyleneglycolmonomethylether acetate were added thereto, followed byconcentrating it again to obtain 78 parts ofpropyleneglycolmonomethylether acetate solution (solid content: 29%) ofresin A1-1, the weight average molecular weight of which was 22100, andin which the content of the unit derived from ethoxyethyl group was38.5%. Resin A1-1 comprises the following structural units.

Synthesis Example 2

To a four-necked flask with a stirring device, a reflux condenser and athermometer, 537 parts of 2,5-xylenol, 107.5 parts of salicylaldehyde,20.9 parts of p-toluenesulfonic acid and 860 parts of methanol werepoured, and heated to make the mixture refluxed and then the temperatureof the mixture was kept for 4 hours. Then the obtained mixture wascooled, and 1440 parts of methylisobutylketone was fed thereto, followedby removing 1120 parts of the mixture therefrom with distilling.

Then 476 parts of m-cresol was added to the residues and heated to 65°C., followed by dropping 571 parts of 37% formalin thereto over 1.5hours while controlling the temperature of the mixture to be 87° C. atthe end of dropping. Then the temperature of the mixture was kept at 87°C. for 10 hours, and then 884 parts of methylisobutylketone was added tothe obtained resin solution, followed by washing it with water threetimes. To the washed resin solution, 3514 parts of methylisobutylketoneand 4647 parts of n-heptane were added and heated to 60° C., and thenstirred for 1 hour, followed by separating therefrom the resin solutionof the bottom layer. To the separated resin solution, 3500 parts ofpropyleneglycolmonomethylether acetate was added to dilute it, followedby concentrating it to give 1520 parts of methylisobutylketone solution(solid content: 30%) of resin A2-2, the weight average molecular weightof which was 7000.

Synthesis Example 3

Three hundred (300 parts) of poly(p-hydroxystyrene) [Trade name, MARUKALYNCUR S2P, made of Maruzen Petrochemical, Co., Ltd.] was dispersed in1200 parts of ion-exchanged water, and then 980 parts of novolak resinA2-2 and 1330 parts of methylisobutylketone were added thereto, followedby removing its aqueous layer therefrom. After concentrating the residueuntil the total amount became 1600 parts, 750 parts ofmethylisobutylketone was added thereto and then concentrated until thetotal amount became 1620 parts. To a four-necked flask with a stirringdevice, a reflux condenser and a thermometer, added were theconcentrated resin mixture, 1400 parts of propyleneglycolmonomethyletheracetate, 980 parts of methylisobutylketone and 0.09 parts ofp-toluenesulfonic acid, then 83 parts of1,4-cyclohexanedimethanoldivinylether, the compound represented byformula (z), was dropped thereinto at a room temperature over 5 minutes.

The obtained mixture was stirred at the room temperature for 5 hours,and 0.16 parts of triethylamine, followed by washing it with 1000 partsof ion-exchanged water five times. The obtained resin solution wasconcentrated until the total amount became 1200 parts, and 2170 parts ofpropyleneglycolmonomethylether acetate were added thereto, followed byconcentrating it until its amount became 2000 parts to give a solution(solid content: 23%) of resin A1-2, the weight average molecular weightof which was 92200.

Synthesis Example 4

To a four-necked flask with a stirring device, a reflux condenser and athermometer, 413.5 parts of 2,5-xylenol, 103.4 parts of salicylaldehyde,20.1 parts of p-toluenesulfonic acid and 826.9 parts of methanol werepoured, and heated to make the mixture refluxed and then the temperatureof the mixture was kept for 4 hours. Then the obtained mixture wascooled, and 1320 parts of methylisobutylketone was fed thereto, followedby removing 1075 parts of the mixture therefrom with distilling.

Then 762.7 parts of m-cresol and 29 parts of 2-tert-butyl-5-methylphenolwere added to the residues and heated to 65° C., followed by dropping678 parts of 37% formalin thereto over 1.5 hours while controlling thetemperature of the mixture to be 87° C. at the end of dropping. Then thetemperature of the mixture was kept at 87° C. for 10 hours, and then1115 parts of methylisobutylketone was added to the obtained resinsolution, followed by washing it with water three times. To the washedresin solution, 500 parts of methylisobutylketone was added, followed bydistilling it under reduced pressure until the amount of solution became3435 parts. To the washed resin solution, 3796 parts ofmethylisobutylketone and 4990 parts of n-heptane were added and heatedto 60° C., and then stirred for 1 hour, followed by separating therefromthe resin solution of the bottom layer. To the separated resin solution,3500 parts of propyleneglycolmonomethylether acetate was added to diluteit, followed by concentrating it to give 1690 parts ofpropyleneglycolmonomethylether acetate solution (solid content: 43%) ofResin A2-1 the weight average molecular weight of which was 7000.

Examples 1 to 12 and Comparative Example 1

The following components were mixed and dissolved in the solvent asshown in Table 1, and further filtrated through a fluorine resin filterhaving pore diameter of 5 μm to prepare photoresist compositions. Thecontents of the components in each example are shown in Table 1.

The symbols recited in Table 1 represent the following components.

<Resin> A1-1: Resin A1-1 A1-2: Resin A1-2 A2-1: Resin A2-1 <AcidGenerator>

B1: N-hydroxynaphtylimidetriflate, represented by formula, trade name“NAI-105”, product by Midori Kagaku, Co., Ltd.

B2: The compound represented by formula, trade name “IRGACURE PAG-103”,product by BASF Japan, Co., Ltd.

<Quencher>

C1: 2,4,5-triphenylimidazole (Product of Tokyo Chemical Industry, Co.,Ltd.)

C2: N,N-dicyclohexylmethylamine (Product of Aldrich Corporation)<Plasticizer>

E1: ethylphthalylethyl glycolate (Product of Tokyo Chemical Industry,Co., Ltd.)

E2: N-butylbenzenesulfoneamide (Product of Tokyo Chemical Industry, Co.,Ltd.)

E3: O-acetyltributyl citrate (Product of Tokyo Chemical Industry, Co.,Ltd.)

E4: Tris(2-ethylhexyl)trimellitate (Product of Tokyo Chemical Industry,Co., Ltd.)

E5: Diisononyl adipate (Product of Tokyo Chemical Industry, Co., Ltd.)

E6: Bis(2-ethylhexyl) sebacate (Product of Tokyo Chemical Industry, Co.,Ltd.)

E7: Dihexyl phthalate (Product of Tokyo Chemical Industry, Co., Ltd.)

<Solvent>

D1: Propyleneglycolmonomethylether acetate

<Surfactant>

S1: Polyether denaturated silicone oil (Toray silicone SH8400; Productof Toray Dow Corning, Co., Ltd.)

TABLE 1 Acid gen- Plas- Sur- Resin erator Quencher ticizer factantSolvent (Kind/ (Kind/ (Kind/ (Kind/ (Kind/ (Kind/ Ex. No. parts) parts)parts) parts) parts) parts) Ex. 1 A1-1/7.425 B1/0.3 C1/0.06 E1/ S1/D1/20 A2-1/6.075 1.35 0.0017 Ex. 2 A1-1/7.425 B1/0.3 C2/0.05 E1/ S1/D1/20 A2-1/6.075 1.35 0.0017 Ex. 3 A1-1/7.425 B1/0.3 C2/0.05 E2/ S1/D1/20 A2-1/6.075 1.35 0.0017 Ex. 4 A1-1/7.425 B1/0.3 C2/0.05 E3/ S1/D1/20 A2-1/6.075 1.35 0.0017 Ex. 5 A1-1/7.425 B1/0.3 C2/0.05 E1/ S1/D1/20 A2-1/6.075 2.7 0.0017 Ex. 6 A1-1/7.425 B1/0.3 C2/0.05 E2/ S1/D1/20 A2-1/6.075 2.7 0.0017 Ex. 7 A1-1/7.425 B1/0.3 C2/0.05 E3/ S1/D1/20 A2-1/6.075 2.7 0.0017 Ex. 8 A1-2/13.5 B1/0.3 C1/0.06 E1/ S1/ D1/201.35 0.0017 Ex. 9 A1-1/7.425 B1/0.3 C2/0.05 E4/ S1/ D1/20 A2-1/6.0751.35 0.0017 Ex. 10 A1-1/7.425 B1/0.3 C2/0.05 E5/ S1/ D1/20 A2-1/6.0751.35 0.0017 Ex. 11 A1-1/7.425 B1/0.3 C2/0.05 E6/ S1/ D1/20 A2-1/6.0751.35 0.0017 Ex. 12 A1-2/13.5 B1/0.3 C2/0.03 E7/ S1/ D1/20 0.78 0.0017Comp. A1-1/7.425 B1/0.3 C2/0.05 None S1/ D1/20 Ex. 1 A2-1/6.075 0.0017

(Preparation of Photoresist Pattern)

Over the substrate (4 inches) where copper had been vapor-deposited on asilicon wafer, each of the photoresist compositions prepared as abovewas spin-coated so that the thickness of the resulting film became 20 μmafter drying. The cupper substrates thus coated with the respectivephotoresist compositions were each prebaked on a direct hotplate at 90°C. for 180 seconds.

Using an i-ray stepper (“NSR 1755i7A” manufactured by Nikon, NA=0.5),each wafer thus formed with the respective film was subjected to 1:1line and space pattern exposure with the exposure quantity being variedstepwise. The exposure was conducted with a mask having line and spacepattern.

After the exposure, each wafer was subjected to paddle development for60 seconds with an aqueous solution of 2.38 wt % tetramethylammoniumhydroxide three times.

(Evaluation)

In this evaluation, the ES (Effective Sensitivity) means the exposurequantity that the line and space pattern with the line width 20 μmbecame a pattern with (line width):(space width) being 1:1 afterexposure through the mask having line and space pattern with the linewidth 20 μm.

I. Cracks

The photoresist patterns were obtained by the process where the exposurewas conducted at the exposure quantity of ES, and then each pattern wasobserved with a scanning electron microscope. Each substrate with theobtained photoresist pattern was left in sequence in thermostatic ovenat 25° C. for two hours, in thermostatic oven at 40° C. for two hours,in thermostatic oven at −5° C. for two hours, in thermostatic oven at40° C. for two hours, and then in thermostatic oven at 23° C. for 24hours. Then the surface of each photoresist pattern was observed duringleaving it at 23° C. The surface where no cracks were observed afterleaving it 23° C. was marked by “◯” (good). The surface where crackswere observed 3 hours after starting to leave it at 23° C. was marked by“X” (bad).

II. Shape

The photoresist patterns were obtained by the process where the exposurewas conducted at the exposure quantity of ES, and then each pattern wasobserved with a scanning electron microscope.

When the profile of pattern was rectangle at both top and bottom sitesas shown in FIG. 1 (a), it was marked by “◯◯” (very good).

When the profile of pattern was a round shape at its top site as shownin FIG. 1( b), it was marked by “◯” (good). When the profile of patternwas a shape whose profile looked like the letter “T” as shown in FIG. 1(c), it was marked by “X” (bad).

III. Resolution

Each of patterns obtained by the process where the exposure wasconducted at the exposure quantity of ES was observed with a scanningelectron microscope. The minimum value of the dissolved line width wasdetermined as its resolution value. The results of the evaluation arelisted in Table 2.

In columns showing the results of profiles, the numbers in theirbrackets represent the value of resolution (μm). In the columns showingthe results of shapes, the symbols (a) to (c) represent the symbols ofthe figures corresponding to each shape.

TABLE 2 Resolution Clacks Shape (μm) Ex. 1 ∘ ∘∘ (a) 10 Ex. 2 ∘ ∘∘ (a) 10Ex. 3 ∘ ∘∘ (a) 10 Ex. 4 ∘ ∘∘ (a) 10 Ex. 5 ∘ ∘∘ (a) 10 Ex. 6 ∘ ∘∘ (a) 10Ex. 7 ∘ ∘∘ (a) 10 Ex. 8 ∘ ∘∘ (a) 10 Ex. 9 ∘ ∘∘ (a) 10 Ex. 10 ∘ ∘∘ (a) 10Ex. 11 ∘ ∘∘ (a) 10 Ex. 12 ∘   ∘ (b) 10 Comp. Ex. 1 x — —

Examples 13 to 15

The components as shown in Table 3 were mixed and dissolved in thesolvent as shown in Table 3, and further filtrated through a fluorineresin filter having pore diameter of 0.5 μm to prepare photoresistcompositions.

TABLE 3 Acid Plas- Sur- Resin generator Quencher ticizer factant SolventEx. (Kind/ (Kind/ (Kind/ (Kind/ (Kind/ (Kind/ No. parts) parts) parts)parts) parts) parts) Ex. A1-1/7.425 B1/0.3 C1/0.06 E1/ S1/ D1/26 13A2-1/6.075 1.35 0.0019 Ex. A1-1/7.425 B2/0.3 C2/0.05 E1/ S1/ D1/26 14A2-1/6.075 1.35 0.0019 Ex. A1-2/13.5 B1/0.3 C1/0.06 E1/ S1/ D1/26 151.35 0.0019

The photoresist patterns were made in the same manner as Examples 1 to12 except that the film thickness after prebake was 5 μm instead of 20μm.

The obtained patterns were evaluated as follow.

In this evaluation, the ES (Effective Sensitivity) means the exposurequantity that the line and space pattern with the line width 3 μm becamea pattern with (line width): (space width) being 1:1 after exposurethrough the mask having line and space pattern with the line width 3 μm.

I. Cracks

The occurrence of cracks was evaluated in the same manner as mentionedabove.

II. Shape

The photoresist patterns having 3 μm of line width were obtained by theprocess where the exposure was conducted at the exposure quantity of theabove-mentioned ES, and then each pattern was observed with a scanningelectron microscope. When the profile of pattern was rectangle at bothtop and bottom sites as shown in FIG. 1 (a), it was marked by “◯” (verygood).

When the profile of pattern was a round shape at its top site as shownin FIG. 1 (b) or when the profile of pattern was a shape whose profilelooked like the letter “T” as shown in FIG. 1 (c), it was marked by “X”(bad).

III. Resolution

Each of patterns obtained by the process where the exposure wasconducted at the exposure quantity of ES was observed with a scanningelectron microscope. The minimum value of the dissolved line width wasdetermined as its resolution value. The results of the evaluation arelisted in Table 4.

In the columns showing the results of shapes, the symbols (a) to (c)represent the symbols of the figures corresponding to each shape.

TABLE 4 Resolution Clacks Shape (μm) Ex. 13 ∘ ∘ (a) 2 Ex. 14 ∘ ∘ (a) 2Ex. 15 ∘ ∘ (a) 2

Examples 16 and 17

The components as shown in Table 5 were mixed and dissolved in thesolvent as shown in Table 5, and further filtrated through a fluorineresin filter having hole diameter of 15 μm to prepare photoresistcompositions.

TABLE 5 Acid Plas- Sur- Resin generator Quencher ticizer factant SolventEx. (Kind/ (Kind/ (Kind/ (Kind/ (Kind/ (Kind/ No. parts) parts) parts)parts) parts) parts) Ex. A1-1/7.425 B1/0.15 C1/0.03 E1/1.35 S1/ D1/14 16A2-1/6.075 0.0014 Ex. A1-2/13.5 B1/0.15 C1/0.03 E1/1.35 S1/ D1/14 170.0014

Over the substrate (4 inches) where copper had been vapor-deposited on asilicon wafer, each of the photoresist compositions prepared as abovewas spin-coated so that the thickness of the resulting film became 50 μmafter drying. The substrates thus coated with the respective photoresistcompositions were each prebaked on a direct hotplate at the 90° C. for300 seconds.

Using an i-ray stepper (“NSR 1755i7A” manufactured by Nikon, NA=0.5),each wafer thus formed with the respective resist film was subjected tocontact hole pattern exposure using a photomask for forming a contacthole pattern having a hole pitch of 100 μm and a hole diameter of 50 μmwith the exposure quantity being varied stepwise.

After the exposure, each wafer was subjected to paddle development for60 seconds with an aqueous solution of 2.38 wt tetramethylammoniumhydroxide three times.

(Evaluation)

The obtained patterns were evaluated as follow.

In this evaluation, the ES (Effective Sensitivity) means the exposurequantity that the contact hole pattern became a pattern with the holediameter 50 μm after exposure through the mask.

I. Cracks

The occurrence of cracks was evaluated in the same manner as mentionedabove.

II. Shape

The photoresist patterns were obtained by the process where the exposurewas conducted at the exposure quantity of ES using the photomask forforming a contact hole pattern, and then each pattern was observed witha scanning electron microscope. In this evaluation, the ES (EffectiveSensitivity) means the exposure quantity which can obtain a contact holepattern having a hole diameter of 50 μm.

When the profile of pattern was rectangle at both top and bottom sitesas shown in FIG. 2 (d), it was marked by “◯” (good). When the profile ofpattern was a round shape at its bottom site as shown in FIG. 2( e), itwas marked by “X” (good).

III. Resolution

Each of patterns obtained by the process where the exposure wasconducted at the exposure quantity of ES was observed with a scanningelectron microscope. The minimum value of dissolved hole diameters wasdetermined as resolution value.

The results of the evaluation are listed in Table 6.

In the columns showing the results of shapes, the symbols (d) and (e)represent the symbols of the figures corresponding to each shape.

TABLE 6 Resolution Clacks Shape (μm) Ex. 16 ∘ ∘ (d) 20 Ex. 17 ∘ ∘ (d) 20

The photoresist composition of the present invention can provide aphotoresist film showing excellent resistance to heat and hardlycracking. Furthermore, the photoresist film obtained from thephotoresist composition can be thick and provide photoresist patternwith excellent shape and resolution.

1. A photoresist composition comprising: a resin which shows an increasein solubility in an aqueous alkali solution by an action of an acid; anacid generator; a plasticizer; and a solvent the amount of which is from40 to 75% by mass of the total amount of the photoresist composition. 2.The photoresist composition according to claim 1, wherein the resin is aresin obtained by reacting a novolak resin, a compound having two ormore vinyloxy groups and a resin comprising a structural unitrepresented by formula (a1-2), a structural unit represented by formula(a2-1), or both of the structural units: wherein Ra1′ and Ra2′ eachindependently represent a hydrogen atom or a C1-C12 hydrocarbon groupwhere a methylene group has optionally been replaced by an oxygen atomor a sulfur atom, Ra3′ represents a C1-C20 hydrocarbon group where amethylene group has optionally been replaced by an oxygen atom or asulfur atom, or one of Ra1′ and Ra2′ is bonded to Ra3′ to form a C2-C20divalent hydrocarbon group where a methylene group has optionally beenreplaced by an oxygen atom or a sulfur atom, and the other represents ahydrogen atom or a C1-C12 hydrocarbon group where a methylene group hasoptionally been replaced by an oxygen atom or a sulfur atom, Ra5represents a hydrogen atom or a methyl group, Ra6 represents a C1-C6alkyl group or a C1-C6 alkoxy group, and m represents an integer of 0 to4, Ra7 represents a hydrogen atom or a methyl group, Ra10 represents aC1-C6 alkyl group or a C1-C6 alkoxy group, and m′ represents an integerof 0 to
 4. 3. The photoresist composition according to claim 1, whichfurther comprises a novolak resin.
 4. The photoresist compositionaccording to claim 1, wherein the acid generator is a compoundrepresented by formula (b5): where Rb1 represents a C1-C18 hydrocarbongroup in which a hydrogen atom has optionally been replaced by afluorine atom and in which a methylene group has optionally beenreplaced by an oxygen atom or a carbonyl group.
 5. The photoresistcomposition according to claim 1, wherein the plasticizer is oneselected from the group consisting of phthalates, aliphatic hydrocarboncarboxylates and aromatic sulfonamides.
 6. A method for producing aphotoresist film with thickness 3 μm to 150 μm, which comprises applyingthe photoresist composition according to claim 1 to a substrate.
 7. Aphotoresist film with thickness 3 μm to 150 μm, which is obtained byapplying the photoresist composition according to claim 1 to asubstrate.
 8. A process for producing a photoresist pattern comprising:(1) a step of applying the photoresist composition according to claim 1on a substrate, (2) a step of forming a photoresist composition film bydrying the photoresist composition, (3) a step of exposing thephotoresist composition film, and (4) a step of developing the exposedphotoresist composition film.
 9. The photoresist composition accordingto claim 2, which further comprises a novolak resin.
 10. The photoresistcomposition according to claim 2, wherein the acid generator is acompound represented by formula (b5): where Rb1 represents a C1-C18hydrocarbon group in which a hydrogen atom has optionally been replacedby a fluorine atom and in which a methylene group has optionally beenreplaced by an oxygen atom or a carboxy group.
 11. The photoresistcomposition according to claim 2, wherein the plasticizer is oneselected from the group consisting of phthalates, aliphatic hydrocarboncarboxylates and aromatic sulfonamides.
 12. A method for producing aphotoresist film with thickness 3 μm to 150 μm, which comprises applyingthe photoresist composition according to claim 2 to a substrate.
 13. Aphotoresist film with thickness 3 μm to 150 μm, which is obtained byapplying the photoresist composition according to claim 2 to asubstrate.
 14. A process for producing a photoresist pattern comprising:(1) a step of applying the photoresist composition according to claim 2on a substrate, (2) a step of forming a photoresist composition film bydrying the photoresist composition, (3) a step of exposing thephotoresist composition film, and (4) a step of developing the exposedphotoresist composition film.